| mikahs |
June 10, 2011 09:00 |
Vortex Street with pisoFoam
Hello people...
I am fairly new to CFD and OpenFOAM, so I am not very sure about some results I am getting while simulating a vortex street with a flow around a cylinder.
I was asked to use pisoFoam with laminar flow, and simulate a given mesh (with the cylinder) at Re=20, Re=200 (the vortex street should appear here) and Re=2000.
At Re=20, I had no problems with convergence, with 8000 Iterations my residuals were below 10E-5.
However at Re=200 and at Re=2000 the residuals oscillate asymptotically.
Example: Re=200
http://img707.imageshack.us/img707/7...erre200.th.jpg
Uploaded with ImageShack.us
I would like to know whether this behaviour in my residuals is normal for vortex street calculations, or if I am really having some problems of some other kind.
Ah, and I forgot to say... Courant-Nr<1 ... :/
Code:
ddtSchemes
{
default Euler;
}
gradSchemes
{
default Gauss linear;
grad(p) Gauss linear;
grad(U) Gauss linear;
}
divSchemes
{
default none;
div(phi,U) Gauss limitedLinearV 1;
div(phi,k) Gauss limitedLinear 1;
div(phi,epsilon) Gauss limitedLinear 1;
div(phi,R) Gauss limitedLinear 1;
div(R) Gauss linear;
div(phi,nuTilda) Gauss limitedLinear 1;
div((nuEff*dev(grad(U).T()))) Gauss linear;
}
laplacianSchemes
{
default none;
laplacian(nuEff,U) Gauss linear corrected;
laplacian((1|A(U)),p) Gauss linear corrected;
laplacian(DkEff,k) Gauss linear corrected;
laplacian(DepsilonEff,epsilon) Gauss linear corrected;
laplacian(DREff,R) Gauss linear corrected;
laplacian(DnuTildaEff,nuTilda) Gauss linear corrected;
}
interpolationSchemes
{
default linear;
interpolate(U) linear;
}
snGradSchemes
{
default corrected;
}
fluxRequired
{
default no;
p ;
}
Code:
solvers
{
p
{
solver PCG;
preconditioner DIC;
tolerance 1e-06;
relTol 0.1;
}
pFinal
{
solver PCG;
preconditioner DIC;
tolerance 1e-06;
relTol 1e-4;
}
U
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-05;
relTol 0;
}
}
PISO
{
nCorrectors 3;
nNonOrthogonalCorrectors 0;
pRefCell 0;
pRefValue 0;
}
|
